The invention relates to a closure device for the vacuum-tight closure of an opening in a wall, comprising a closure unit, which closure unit has a closure element, which closure element is adjustable parallel to a longitudinal adjustment direction from an open position, that the closure element assumes in an opened state of the closure device, into an intermediate position, and parallel to a transverse adjustment direction, that lies at right angles to the longitudinal adjustment direction, from the intermediate position into a closed position, that the closure element assumes in a closed state of the closure device, and which closure unit has at least one rod that has a longitudinal axis lying parallel to the longitudinal adjustment direction and that projects out of a housing of the closure device and that, outside the housing, supports the closure element and that is rigidly connected to a carrier piece, a transmission unit that, by way of a drive, is adjustable parallel to the longitudinal adjustment direction between an initial position, in which the closure element assumes the open position, a middle position, in which the closure element assumes the intermediate position, and an end position, in which the closure element assumes the closed position, at least one spring that is arranged between the transmission unit and the carrier piece and that drives the carrier piece along during the adjustment of the transmission unit from the initial position into the middle position, with the carrier piece being adjusted relative to the housing in the longitudinal adjustment direction, and a stop device that, during the adjustment of the transmission unit from the middle position into the end position, blocks a further adjustment of the carrier piece parallel to the longitudinal adjustment direction, with the carrier piece being adjusted relative to the housing in the transverse adjustment direction.
A closure device for the vacuum-tight closure of an opening in a wall may also be referred to as a vacuum valve. If the opening is arranged on the wall of a vacuum chamber and the closure element is situated on the outer side of the chamber wall in the surroundings space surrounding the vacuum chamber, such a type of vacuum valve is also referred to as a vacuum door. A closure device of said type in the form of a vacuum door can be designed for pressure difference acting only in one direction. Other types of vacuum valves are normally designed for pressure differences acting in both directions. In the case of such closure devices, the closure element is generally arranged in a valve housing which has a valve opening which is closable by the closure element.
Closure devices in the case of which, in order to close the opening, the closure element is firstly adjusted, in a longitudinal adjustment direction lying parallel to the rod, from an open position into an intermediate position in which the closure element covers the opening but is still raised from the wall, and is subsequently adjusted in a transverse direction lying at least substantially at right angles to the longitudinal adjustment direction and is pressed against the wall, are also referred to as L-valves.
In a non-generic type of construction of L-valves, the rod is mounted so as to be pivotable about an axis perpendicular to the longitudinal adjustment direction, in order to permit the adjustment of the closure element from its intermediate position into its closed position and back again. For the pivoting of the rod about the axis, use may be made here of slotted guides, such as is known for example from U.S. Pat. No. 6,237,892 B1, U.S. Pat. No. 7,066,443 B2 or US 2012/0258242 A1.
In the case of L valves in which, for the adjustment of the closure element between the intermediate position and the closed position, a parallel displacement of the closure element takes place in a transverse adjustment direction at an angle, in particular at right angles, with respect to the longitudinal adjustment direction, it is the case in a conventional embodiment that drive elements for the adjustment of the closure element between the intermediate position and the closed position are arranged on a carrier unit which supports the closure element, wherein the carrier unit is attached to a rod. Such embodiments of L valves, inter alia in the form of vacuum doors, emerge for example from U.S. Pat. No. 6,056,266 A, U.S. Pat. No. 6,899,316 B2 and U.S. Pat. No. 7,611,122 B2. Here, U.S. Pat. No. 6,056,266 A, U.S. Pat. No. 7,611,122 B2 also disclose sequence controllers for the purposes of ensuring the correct sequence of the actuation of the piston-cylinder units. A further such sequence controller for an L-valve emerges from U.S. Pat. No. 8,177,190 B2.
WO 2010/034046 A1 discloses an L-valve in which a block which serves for displaceably mounting the rod in the longitudinal adjustment direction and to which the drive for the adjustment of the rod in the longitudinal adjustment direction is also attached is mounted so as to be linearly displaceable in a transverse adjustment direction lying at right angles to the longitudinal adjustment direction. This linear displacement is performed by way of piston-cylinder units which act in said direction.
U.S. Pat. No. 7,762,527 B2 presents an embodiment of an L-valve in which the piston-cylinder unit which serves for the adjustment of the closure element in the longitudinal adjustment direction is mounted, by way of a linear guide, so as to be displaceable relative to a valve housing in the transverse adjustment direction lying at right angles to the longitudinal adjustment direction.
WO 2014/075757 A1 discloses a valve in which the rod which supports the closure element is guided so as to be linearly displaceable in the longitudinal adjustment direction. For this purpose, a carrier piece is provided which is connected to the valve rod and which is guided along rod-like guide parts so as to be displaceable in the longitudinal adjustment direction. The rod-like guide parts are displaceable in a transverse direction at right angles to the longitudinal adjustment direction, and can be displaced in the transverse adjustment direction by way of pneumatic piston-cylinder units. For the displacement of the rod in the longitudinal adjustment direction, use is likewise made of pneumatic piston-cylinder units, the piston rods of which are connected to the carrier piece, wherein said connection permits mobility of the transmission piece relative to the piston rods in the transverse adjustment direction.
US 2013/0112906 A1 presents a closure device of the type mentioned in the introduction. The closure element is arranged in a valve housing and, in the closed position, closes an opening in the valve housing. For the opening and closing of the closure device, use is made of piston-cylinder units which displays a transmission unit parallel to a longitudinal adjustment direction between an initial position, a middle position and an end position. The transmission unit is formed by a yoke to which left-hand and right-hand cam drivers, which protrude in the longitudinal adjustment direction, are fixed. In a respective cam driver there is arranged in each case one first cam recess, which extends in the longitudinal adjustment direction, and one second cam recess, which extends in the oblique adjustment direction. Control cams which are arranged fixedly on a housing engage into the first cam recesses. Control cams which are arranged on a carrier piece which is rigidly connected to a rod which supports the closure element engage into the second cam recesses. A spring is arranged between the yoke of the transmission unit and the carrier piece. This yoke drives the carrier piece along during the adjustment of the transmission unit from the initial position into the middle position. During a further displacement of the transmission unit from the middle position into the end position, a further movement of the carrier piece in the longitudinal adjustment direction is blocked, and the carrier piece is adjusted in the transverse adjustment direction lying at right angles to the longitudinal adjustment direction. In this way, the rod, and with it the closure element, are also displaced parallel to the transverse adjustment direction in order to move the closure element into the closed position. In the case of said closure device, it appears to be difficult to realize a smooth movement sequence with little play without great outlay in terms construction.
A similar closure device emerges from EP 1 061 301 A2. Here, however, during the adjustment of the transmission unit from the middle position into the end position, the rods which support the closure element pivot about an axis lying at right angles to the longitudinal adjustment direction. Such pivoting has disadvantages in relation to a parallel displacement of the closure element, for example with regard to uniform compression of the seal of the closure element in the closed position thereof.
US 2015/0014556 A1 discloses a further closure device which is similar to the closure device of US 2013/0112906 A1. A difference of the closure device in this document consists in that first and second closure elements are provided, by way of which openings in opposite walls can be selectively closed off.
JP H112360 A discloses a closure device in the case of which an adjustment of the closure element from an open position via an intermediate position into a closed position is likewise realized by way of a drive acting in a longitudinal direction. The adjustment of the closure element from the intermediate position into the closed position is in this case realized by virtue of the valve rod to which the closure element being pivoted, by virtue of first cams being displaced in first slots extending parallel to the longitudinal direction and second cams being displaced in second slots extending obliquely with respect to the longitudinal direction.